JPH03242037A - Test equipment for communication line - Google Patents

Abstract

PURPOSE:To easily and early detect the presence of an induction fault of a cable or its cause by conducting a simulating induction test to the cable so as to recognize the balance state of the cable. CONSTITUTION:Test signals S1a, S1b in a prescribed phase relation are applied to one terminal T of two electric wires 4a, 4b of a cable (communication line) 4 by a test signal application section 2. When the communication line 4 is unbalanced, the relation of the phase of input signals S2a, S2b appearing at the other terminal R is changed to the relation of the phase of the test signals S1a, S1b. A detection section 21 detects its state of change and the display by the display section 25 is implemented based on an output S3 from the detection section 21. Thus, the presence of an induction fault or its cause of the communication line 4 is easily and early found out.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a communication line testing device used for communication lines such as telephone lines and data lines, and is capable of early and easily discovering the presence or absence of induction disturbances in the lines and their causes. The purpose of the present invention is to provide a test signal application unit for applying test signals having a certain phase relationship to each other from one end side of at least two electric wires of a communication line consisting of a plurality of electric wires; a detection unit connected to the other ends of two electric wires to which a test signal is applied, and detects a state of change in the mutual phase relationship of the input signals from the respective electric wires with respect to the test signal; and an output from the detection unit. and a display section that performs display based on.

[Industrial application field]

The present invention relates to a testing device for communication lines used in communication lines such as telephone lines and data lines.

In recent years, data communication systems in which a computer and a large number of terminal devices are connected through communication lines have become rapidly popular.

In general, light and shadow cables and coaxial cables are often used as lines for communication lines, but if a problem occurs in these lines, computers and terminal devices connected to the line may malfunction. This, combined with the increasing number of lines being multiplexed, has an extremely large social impact.

Therefore, it is extremely important to prevent line failures and to promptly remove the failures should they occur.

[Prior Art] Communication lines (hereinafter referred to as "lines") are laid in various routes such as overhead, underground, and inside buildings, but they are often subject to induced disturbances from electrical equipment near the lines. .

For example, many electrical machines, such as electric heaters, automatic doors, and freezers, are used in buildings where railroad tracks are laid, and these can cause problems in guiding the railroad tracks. In particular, in recent years, high-frequency inverters have been widely used to increase the efficiency of electric motors, and the situation is such that induction disturbances are likely to occur.

In the past, in order to prevent or detect line failures,
Line tests are carried out using various testing machines, such as resistance or voltage measurements using circuit testers and insulation resistance measurements using insulation testers.

[Problems to be Solved by the Invention] However, since railroad tracks are generally used during the day, such railroad tests are conducted at night. In this case, many of the electrical machines that are the cause of induction failures are stopped, and it is extremely difficult to discover whether there is an induction failure or its cause.

For example, when a light-and-shadow cable or a quad-shaped cable is used as a line, even if the insulation condition of one core wire deteriorates, the balance will be lost and the cable will be more susceptible to inductive disturbances.

Deterioration of the insulation condition can be detected by measuring insulation resistance using an insulation tester, but since high voltages of several hundred volts are used to measure insulation resistance, it is possible to accidentally damage computers, terminal equipment, etc. that fail to be disconnected from the line. Sometimes I end up doing it. For fear of this, insulation resistance measurements are rarely carried out other than for inspections after the completion of new line construction, and it has not been easy to discover the cause of induction disturbances.

Also, if an unbalanced branch line is connected in the middle of the FL path, or some type of equipment is connected to one end of the branch line, the balance of the line will be disrupted and induction disturbances may occur. However, it is not easy to discover such a state as described above.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a communication line testing device that can quickly and easily discover the presence or absence of an induction fault in a line or its cause.

[Means to solve the problem]

In order to solve the above-mentioned problems, the test device according to the present invention has the following features:
As shown in FIG. 1, test signals S1a) (S1b, S
A test signal applying section 2 that applies lb, and the test signal S1
a) (Two if lines 4a to which S1b and Slb are applied,
4b, and each 74jlIj! 4
the test signal S1a) of the input signals S2a and S2b from a and 4b;
Display unit 25.2 that displays based on the output S3 from 1
7.

C Effect] The test signal application unit 2 applies test signals S1a) (S1b, Slb) having a constant phase relationship to each other from one end side T of at least two electric wires 4a, 4b of the communication line 4.

If the communication line 4 is unbalanced, the phase relationship between the input signals S2a and S2b appearing at the other end R is the test signal S1a)(S
It changes with respect to the phase relationship between 1b and Slb.

Furthermore, the phase relationship between the test signals S1a) (S1b and Slb itself may change).

The detecting section 21 detects the change state, and based on the output S3 from the detecting section 21, a display is performed on the display section 25.27.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a test apparatus 1 showing an embodiment of the present invention.

The test device 1 is composed of an independently portable handset 2 and a parent 813, each of which is connected to both ends of a light and shadow cable 4.

The slave unit 2 receives an oscillation signal S consisting of a sine wave of about IKHz.
0 oscillator number S provided with an oscillator 11 that outputs l
1 is connected to one end side T4a, T4b of each of the two electric wires 4a, 4b of the cable 4 (this is sometimes referred to as "one end side T") through resistors H12, 13 having the same resistance value. It is connected.

As a result, test signals S1a and Slb having the same phase and amplitude are applied from one end side T4a and T4b of the cable 4.

The base device 3 is provided with a differential amplifier 21, a rectifier 22, an AD converter 23, a control section 24, a display section 25, a key input section 26, and the like.

The differential amplifier 21 is connected to the other end sides R4a and R4b (this may be referred to as "the other end side R") of the electric wires 4a and 4b, respectively. The differential amplifier 21 receives input signals S2a and S2b that are manually input from the other end sides R4a and R4b.
are differentially amplified and a difference signal S3 corresponding to the difference between them is output.

Therefore, if the cable 4 is completely balanced, the input signals S2a and S2b input to the differential amplifier 21
are in the same phase and have the same amplitude, so the difference signal S3 becomes zero. However, if the balance of the cable 4 is disrupted, the phase and voltage of the input signal 52aS2b will shift accordingly.
A non-zero signal appears as the difference signal S3.

Note that when the cable 4 is unbalanced, the phases and voltages of the test signals S1a and Slb themselves may shift, but even in that case, the phase relationship between the input signals S2a and S2b is based on the test signal S1a) (S1b .

It may be considered that there is some change to Slb.

The rectifier 22 receives the difference signal S output from the differential amplifier 21.
3 is rectified and smoothed with an appropriate time constant to obtain a DC signal S4.
Output.

The AD converter 23 quantizes the DC signal S4 output from the rectifier 22, and converts it into detection data D1 of a digital value corresponding to the voltage value of the DC signal S4.

The control unit 24 stores detection data D1 manually input from the AD converter 23, and displays the display unit 25 based on the detection data D1.
The contents are displayed on the printer 27, and the contents are printed by an externally connected printer 27 as necessary.

The display unit 25 includes, for example, a liquid crystal display,
Display numbers, messages, etc.

The key manual section 26 consists of a numeric keypad, control keys, etc.
This allows setting data, command data, etc. to be input.

The control unit 24 performs appropriate calculations on the detection data D1, compares it with certain reference data, and if the detection data DI is larger, it indicates that the cable 4 is unbalanced. The message is displayed on the display section 25.

Therefore, it is possible to perform a pseudo-induction test on the cable 4 using the above-mentioned test equipment W1, and thereby the equilibrium state of the cable 4 can be easily determined. It is possible to easily know whether the degree of unbalance of cable 4 is within a permissible range or whether the cable 4 is within a permissible range in which the cable 4 is not subject to inductive disturbances.

This allows you to check the status of the cable 4, the presence or absence and status of branch lines connected to the cable 4, the presence or absence of unbalanced devices connected to the cable 4, the presence or absence of devices connected only to one side of the wires 4a4b, etc. Inductive disturbances in the cable 4 can be easily removed by inspecting them in detail, removing those branch lines and equipment, or replacing the cable 4 as necessary.

Therefore, it is possible to improve the reliability of determining whether the cable 4 is good or bad, prevent the occurrence of failures, and quickly take measures against accidents caused by failures, such as searching for the failure location or cause of the failure after the failure occurs. This makes it possible to significantly reduce time and costs caused by failures in the cable 4, and to improve the reliability of the data communication system.

In the embodiments described above, the frequency, waveform, and voltage of the oscillation signal St output by the oscillator 11 may be various other than those described above. Furthermore, if the phases of the test signal 51a) (S1b and S1b applied to one end side T are the same as in the above-mentioned embodiment, the configuration of the slave unit 2 and the base unit 3 will be simplified, but this phase has a certain relationship. If necessary, the @I!3 side is configured to detect a change in the phase relationship between the input signals S2a and S2b from the phase relationship between the test signals S1a and Slb, or an amount corresponding to the amount of change. Just do it.

In the embodiments described above, the reference data may be set by the key manual unit 26, or may be selected from a plurality of predetermined reference data. operational amplifier 21
Depending on the level of the difference signal S3 from the rectifier 2, the difference signal S3 may be amplified by a suitable amplifier.
2 is omitted, the difference signal S3 output from the differential amplifier 21 is directly converted into digital value data, and this data is analyzed by the control unit 24, thereby elucidating the state of the cable 4 in more detail and removing the fault. can be done more quickly.

Alternatively, the difference signal S3 from the differential amplifier 21 may be compared with a reference level using a suitable comparator, and an alarm may be output when the difference signal S3 is greater than the reference level.

As the display unit 25, a plasma display or a CRT may be used.Instead of or in addition to the display by the display unit 25 or the printer 27, another indicator light is turned on,
It can also be displayed by various display means, such as by sounding an alarm buzzer.

In the example described above, the child I for performing the M low induction test
12 and parent [13 may have various configurations other than those described above. In addition, in the handset 2 and the parent IR 3,
It is also possible to provide devices with various functions, such as a switching device that sequentially switches connections to a large number of cables 4 for testing, devices for performing other tests, and communication devices for making calls between each other. It is possible.

The above-mentioned test equipment 1 can be used to test various cables other than the commercial cable 4, various cables laid outside buildings such as overhead or underground cables, telephones, telegraphs, railway signals, clocks, fire departments, cable vision, etc. It can be used to test various lines such as cables used for communication.

〔Effect of the invention〕

According to the present invention, it is possible to provide a communication line testing device that can quickly and easily discover the presence or absence of an induction fault in a line or its cause.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a test device showing an embodiment of the present invention. In the figure, 2 is a slave device (test signal application section), 4 is a cable (communication line), 4a and 4b are 1f lines, 21 is a differential amplifier (detection section), 25 is a display section, and 27 is a printer (display section) , T is for one end, R is for the other end, S1a) (S1b, Slb are test signals, S2a, S2b
is the input signal, and S3 is the difference signal (output).

Claims (1)

[Claims] (1) Applying test signals (S1a) (S1b) having a certain phase relationship to each other from one end side (T) of at least two electric wires (4a) (4b) of a communication line (4) consisting of a plurality of electric wires. The test signal applying section (2) is connected to the other end side (R) of the two electric wires (4a) (4b) to which the test signals (S1a) (S1b) are applied, and each of the electric wires (4a) ( 4b) input signal from (S2a) (S
2b) of the test signals (S1a) (S
1b); and display units (25) and (27) that display based on the output (S3) from the detection unit (21). Communication line testing equipment.